Townes was appointed Professor in 1950 at Columbia University.[2] He served as Executive Director of the Columbia Radiation Laboratory from 1950 to 1952. He was Chairman of the Physics Department from 1952 to 1955.[2]

On April 26, 1951, while in Washington DC for a meeting of the Navy Millimeter Committee, he rose early and at 6 AM sat on a park bench in Washington DC's Franklin Park. While watching the azaleas in full bloom, he mused over his committee work and conceived a new way to apply the laws of physics to create intense, precise beams of coherent radiation. He coined the term maser for Microwave Amplification by Stimulated Emission of Radiation, and when the same principle was applied to higher frequencies the term laser was used.[18] Theorists like Niels Bohr and John von Neumann doubted whether it was possible to create such a thing as a maser.[19] Nobel laureates Isidor Isaac Rabi and Polykarp Kusch received the budget for their research from the same source as Townes. Three months before the first successful experiment, they tried to stop him: "Look, you should stop the work you are doing. It isn't going to work. You know it's not going to work, we know it's not going to work. You're wasting money, Just stop!"[20]

From 1959 to 1961, he was on leave of absence from Columbia University to serve as Vice President and Director of Research of the Institute for Defense Analyses in Washington, D.C., a nonprofit organization which advised the U.S. government and was operated by eleven universities.[2] Between 1961 and 1967 Townes served as both Provost and Professor of Physics at the Massachusetts Institute of Technology.[2] Then, in 1967, he was appointed as a Professor of Physics at the University of California at Berkeley, where he remained for almost 50 years; his status was as professor emeritus by the time of his death in 2015.[2] Between 1966 and 1970, he was chairman of the NASA Science Advisory Committee for the Apollo lunar landing program.

Townes married his wife Frances H. Brown in 1941.[2] They lived in Berkeley, California.[2] They had four daughters, Linda Rosenwein, Ellen Anderson, Carla Kessler, and Holly Townes.[2]

A religious man and a member of the United Church of Christ, Townes believed that "science and religion [are] quite parallel, much more similar than most people think and that in the long run, they must converge".[26] He wrote in a statement after winning the Templeton Prize in 2005: “Science tries to understand what our universe is like and how it works, including us humans. Religion is aimed at understanding the purpose and meaning of our universe, including our own lives. If the universe has a purpose or meaning, this must be reflected in its structure and functioning, and hence in science.”[27]

Townes died at the age of 99 in Oakland, California, on January 27, 2015.[1][28] “He was one of the most important experimental physicists of the last century,” Reinhard Genzel, a professor of physics at Berkeley, said of Townes. “His strength was his curiosity and his unshakable optimism, based on his deep Christian spirituality.”[27]